Celiac Disease (CD) is wheat intolerance to foods containing wheat, oats, rye or barley. It develops when the body's own immune system attacks the small intestines, damaging the lining of the intestinal wall; hence preventing absorption of nutrients into blood stream. The protocol is based on our principal hypothesis that celiac disease (CD) is as prevalent in the United States as it is in Europe, however it is under diagnosed due to mild presentation in the majority of the cases and lack of a comprehensive screening program in high risk groups. Celiac disease is the most frequent autoimmune disease of the digestive system, begins in early childhood and can only be controlled by life-long dietary restrictions. The reason it is unique among other autoimmune diseases is that a causative environmental factor is known and its elimination removes symptoms of the disease and prevents long term complications such as severe malnutrition, growth impairment, and malignancies. Unfortunately, most of the CD patients in the United States remain undiagnosed and untreated; therefore large groups of high risk individuals need to be studied to reveal the full spectrum of the disease, to identify genetic and environmental factors, and develop optimal screening and prevention strategies. Our group is in a unique position to meet these goals by studying two already existing population-based cohorts of persons at high risk of CD: 1) general population screened for genes (HLA alleles) associated with CD (R01, DK-32493, 1993-2001 Marian Rewers, P.I.); and 2) a large population of patients with type 1 diabetes and their relatives followed by the Barbara Davis Center for Childhood Diabetes in Denver. These two groups are tested for Transglutaminase antibody (TgIgA), an indicator that the immune system is attacking the intestinal wall. By enrolling people who are at increased risk we hope to a) establish a non-invasive means of testing for celiac disease; b) determine the prevalence of celiac disease in the United States through selected morphological and immunological features of CD in intestinal biopsies on children positive for EMA or Tg; c) document variations of symptoms between individuals; and d) determine which environmental and genetic characteristics that influence development of CD.